Berkeley Lab and SLAC Host Hard X-Ray Photoemission Conference

Earlier this month, Berkeley Lab and SLAC hosted the 7th International Conference on Hard X-Ray Photoelectron Spectroscopy (HAXPES). This biennial meeting has grown from a small workshop held at ESRF in 2003 with about 50 participants, to a truly international event, which this year attracted 150 participants from 20 countries. This year’s event was co-chaired by Chuck Fadley (Materials Sciences Division, Berkeley Lab, and UC Davis), Zahid Hussain (ALS, Berkeley Lab), and Piero Pianetta (Stanford University and SLAC).

Group photograph of the conference participants at the Berkeley Marina.

HAXPES is a new aspect of photoemission that uses hard x-rays with energies of roughly 2–10 keV. Compared to the traditional photoemission energies of ~10 eV–1.5 keV, these higher energies permit measuring properties more characteristic of the bulk, rather than the surface, of a given material. These energies also reveal the buried interfaces that are ubiquitous in nanostructured and multilayered systems. The range of applications of HAXPES is thus very broad, from fundamental studies of strongly correlated and magnetic materials and their interfaces, to operando investigations of model devices and surface interactions at high ambient pressures, to real world industrial systems and processes.

There are approximately 25 HAXPES facilities at synchrotrons around the world, with the number steadily growing. Beamline 9.3.1 at the ALS provides HAXPES capabilities for both condensed matter and ambient-pressure experiments and is currently being upgraded to increase flux and stability. First HAXPES results are also being reported from free-electron lasers.

The topics covered in the talks and posters at the conference were, likewise, very wide ranging, including:

First measurements of time-resolved photoemission at the psec to fsec time scales, using both synchrotrons and FELs; and

New opportunities for soft- and hard- x-ray photoemission at both synchrotrons and free-electron lasers, with talks and posters that covered all existing, newly commissioned and planned facilities, including ALS-U, LCLS-II, and others.

(Top) One of the highly attended sessions in progress. (Bottom, L to R) Consulting with one of the exhibitors. Discussions in a poster sessions on new applications of HAXPES.

A student poster competition, funded by Elsevier through the Journal of Electron Spectroscopy and Related Phenomena, was held. The winners were Ravini Chandresena (Temple University) and Erik Schaefer (Johannes Gutenberg University Mainz).

Tours of both SLAC, including SSRL and LCLS, and the ALS were also part of the program. The conference banquet was held at SLAC and included Hawaiian entertainment and a talk by Ingolf Lindau on the origins of HAXPES.

The conference was bookended by an initial overview of the field by Wolfgang Drube (DESY) and a final discussion of highlights by Ralph Claessen (University of Wurzburg) and Hao Tjeng (Max Planck Institute Dresden). Abstracts and slides from talks are available on the website.

(Left) Tour of the LCLS. (Right) Hula by Susan Fadley.

Financial support was provided by the ALS, SLAC, NSLS-II, APS, and UC Davis, and by the following exhibitors: Scienta/Omicron, Focus, SPECS, MBS, Inficon/Instrutech, Fermi Instruments, Prevac, RoSo Intruments, and Sigray. It was also endorsed by MRS, AVS, and IUVSTA.

The next HAXPES conference will go to Paris in 2019, hosted by Soleil Synchrotron and the Université Pierre et Marie Curie.

The Advanced Light Source is a U.S. Department of Energy (DOE) Scientific User Facility supported by the Director, Office of Science, Office of Basic Energy Sciences and operated for the DOE Office of Science by Lawrence Berkeley National Laboratory.